Work will be continued on the carbohydrate metabolism of sympathetic and dorsal root ganglia of chicken embryos, using specifically labeled glucose as a tracer. We will try to develop a preparation suitable for studying the effects of neuronal activity on such metabolism at an embryonic age at which the pentose cycle is operating, in order to assess the possible role of this cycle in providing energy for conduction and transmission of impulses. We will also apply our new criteria for pentose cycle activity, based on differences between time courses of the rates of outputs of carbons 1 and 6 of glucose into CO2, to older ganglia, in order to see if the pentose cycle may be operating in mature nervous tissue, contrary to common belief.